Thought I would just bring this subject up (probably again) I just purchased a gorgeous little Betta yesterday a young one. I am so sick of shops telling me that they don't need heaters, or anything other than the usual cup/bowl. I am stressing a bit about the heater. Some people say 25w too big and can caused damage in a 5gal tank, (mine holds almost 5). Though with gravel etc it is less. I have had the light is enough heater thing as well. I am wondering if anyone on the forum admits to not using a heater, and if so how the fish survive?? I only know a couple of people who have a Betta and neither use heaters. Both 6 months old and both doing really well. ???